Use of magnetics with magnetizable abrasive particles, methods, apparatuses and systems using magnetics to make abrasive articles

Abstract

According to one embodiment, a method of making an abrasive layer on a backing is disclosed. The method can comprise: providing a distribution tool having a dispensing surface with cavities, providing a backing having a first major surface, supplying magnetizable abrasive particles to the dispensing surface such that at least one of the magnetizable abrasive particles is disposed in a respective one of the cavities, applying a magnetic field to retain the magnetizable abrasive particles disposed in the cavities, aligning the backing with the dispensing surface with the first major surface facing the dispensing surface, transferring the magnetizable abrasive particles from the cavities to the backing, sequent to or simultaneous with transferring the abrasive particles, removing or changing a magnetic field so the magnetic field no longer retains the magnetizable abrasive particles in the cavities.

The invention claimed is: 
     
       1. A method of making a coated abrasive article comprising the steps:
 providing a distribution tool having a dispensing surface with cavities; 
 providing a backing having a first major surface, the backing comprising a layer of a first curable binder precursor disposed on at least a portion of the first major surface; 
 supplying magnetizable abrasive particles to the dispensing surface such that at least one of the magnetizable abrasive particles is disposed in a respective one of the cavities, wherein during the supplying step the dispensing surface is positioned to allow the force of gravity to slide the magnetizable abrasive particles into the cavities; 
 applying a first magnetic field to retain the magnetizable abrasive particles disposed in the cavities; 
 inverting the distribution tool relative to the backing such that the magnetizable abrasive particles are retained by the first magnetic field against the force of gravity; 
 aligning the backing with the dispensing surface with the first major surface facing the dispensing surface and has a distance from the dispensing surface to keep the backing from contacting the dispensing surface; 
 applying a second magnetic field to urge the magnetizable abrasive particles out from the cavities 
 onto the backing and attaching the magnetizable abrasive particles to the first curable binder precursor layer; and 
 at least partially curing the layer of the first curable binder material precursor to provide an at least partially cured abrasive layer secured to the backing. 
 
     
     
       2. The method of  claim 1 , further comprising disposing a second curable binder material precursor onto the at least partially cured abrasive layer, and at least partially curing the second curable binder material precursor. 
     
     
       3. The method of  claim 1 , further comprising:
 supplying an excess of magnetizable abrasive particles to the dispensing surface such that more magnetizable abrasive particles are provided than the number of cavities, wherein a majority of the cavities have at least one of the magnetizable abrasive particles disposed therein; and 
 removing at least a portion of the excess magnetizable abrasive particles not disposed within a cavity. 
 
     
     
       4. The method of  claim 1 , further comprising urging the magnetizable abrasive particles to direct the magnetizable abrasive particles into the cavities using the magnetic field. 
     
     
       5. The method of  claim 1 , wherein the magnetizable abrasive particles face the first major surface prior to or during transferring the magnetizable abrasive particles from the cavities. 
     
     
       6. The method of  claim 5 , wherein during the transferring, the force of gravity allows the magnetizable abrasive particles to slide out of the cavities. 
     
     
       7. The method of  claim 1 , wherein removing or changing the magnetic field includes at least one of: reversing a polarity of the magnetic field to push the magnetizable abrasive particles out of the cavities, moving the distribution tool relative to magnetic tool to reduce the magnetic field, eliminating the magnetic field by switching off an electromagnet that produces the magnetic field, or providing a second magnetic field of greater
 strength than and in substantially opposing direction from the magnetic field to push the magnetizable abrasive particles out of the cavities. 
 
     
     
       8. The method of  claim 1 , wherein the magnetizable abrasive particles comprise triangular platelets.